Non-invasive medical probe provided with suction cup

ABSTRACT

A non-invasive medical probe for monitoring a patient&#39;s condition in particular an intra-uterine device for monitoring fetal condition is featured. The medical probe includes a resilient walled suction cup having a peripheral rim for application to a patent&#39;s skin, a pump adapted for connection to the cup for evacuating the cup to adhere the cup to the patient&#39;s skin, and a pair of non-invasive skin contact electrodes for connection to diagnostic apparatus. One of the electrodes is disposed on a mounting located centrally within the cup to leave a channel to be evacuated by the pump and the second electrode is disposed externally of the cup adjacent to the cup to provide a second contact in the vicinity of the first electrode.

FIELD OF THE INVENTION

This invention relates to non-invasive medical probes for monitoring apatient's condition and to suction cups therefor.

BACKGROUND DISCUSSION

It is commonly required in medical fields to secure a probe including anelectrode adjacent the surface of a patient's skin for measuring andmonitoring purposes. It is also desirable to secure an electrodeadjacent the scalp of a fetus or a neonate without such securing causingtrauma to the patient, as is conventionally caused by invasion of thefetus or neonate.

FR-A-2569976 discloses a resilient suction member for securing anelectrode adjacent the surface of a patient's skin, in which a resilientboss has secured therein a plurality of concentrically mountedelectrodes one of which, namely a monitoring pick-up, is exposed on theface of the boss which is applied to the skin. The exposed electrode issurrounded by three concentric, shallow channels formed in the otherwiseflat face of the boss. The channels are connected via passageways to asource of sub-atmospheric pressure in the form of a vacuum pump so that,when the face of the boss is applied to the skin, the chamber formed bythe channels and the skin may be evacuated with the result that theboss, and hence the electrode, is secured by suction against the skin.

The suction member of FR-A-2569976 suffers the disadvantage that thechannels are necessarily small dimensions when the suction member itselfis manufactured small enough for application to the scalp of a neonateor a prenatal fetus. Consequently the area of scalp over which thereduced pressure in the channels acts, and hence the downward securingforce, is small. This downward force is spread over a multiplicity ofupwardly directed supporting rings with the result that the sealingeffect of the suction member is small. To overcome the prospect ofresulting leakage, the source of sub-atmospheric pressure required toretain the monitoring pick-up in secure contact with the monitoredsurface, has to be one which can pump out the cavity indefinitely, i.e.a mechanical/electrical pump. Such pumps are costly and bulky. Thisarrangement may be uncomfortable for the patient, and it is in additionfrequently required to supplement the securing action of the suctionmember with surgical adhesive tape as the suction created in a smallsuction member is barely sufficient to retain the electrode adjacent thescalp. For these reasons it is believed that this proposed suctionmember has not achieved practical use, especially in connection with themonitoring of a pre-natal fetus or as an intra-uterine device.

U.S. Pat. No. 4,217,908 and U.S. Pat. No. 4,369,793 disclose medicalinstrumentation electrode apparatus for use in connecting wiring from anexternal medical instrument such as an electrocardiograph machine withan area of a patient's skin. The apparatus includes a vacuum bell whichis interconnectible with a resilient bulb for partially evacuating thesame and causing a pliable ring disposed on the open end of the bell tocollapse against a patient's skin. In this manner a disposable contactheld in place within the vacuum bell by a core portion of the bell isheld in electrical contact with the skin area. The core portion isintegrally formed with the vacuum bell and includes an upper protrudingend for connection with the resilient bulb and is further provided withan air communicating passage extending between the bulb and the interiorof the vacuum bell. A single electric contact is provided for connectinga wire from an electrocardiograph machine to the contact.

WO-A-85/00018 discloses an electrode unit for use in electrotherapycomprising a cup that is collapsible by suction applied to a pipe thatforms the stem of an electrode disc within the cup. Conduits communicatethe inside of the cup through a boss with the atmosphere through anexternal groove. A sleeve extends from the boss and has acircumferential rib or flange. The sleeve can be folded back to engagethe flange into the groove to block off the conduits which connect toatmosphere to permit the cup to collapse when the rim of the cup isplaced against the body of a patient and suction is applied, and thesleeve can be lifted up to admit air into the conduits in order torelease the cup.

It will be appreciated that none of the arrangements described in theaforesaid US and International references would be suitable forapplication to the head of an unborn fetus located in the mother'suterus for monitoring the condition of the fetus.

SUMMARY OF THE INVENTION

This invention provides a non-invasive medical probe for monitoring apatient's condition comprising a resilient walled suction cup having aperipheral rim for application to a patients skin, the cup being adaptedfor connection to a source of suction for evacuating the cup to securethe cup to the patient's skin, and a pair of non-invasive skin contactelectrodes for connection to diagnostic apparatus, one of the electrodesbeing disposed internally within the cup on a mounting located centrallywithin the cup to leave a channel encircling the electrode within theperipheral rim to be evacuated for securing the cup to the skin, and thesecond electrode being disposed on an external surface of the probeadjacent to the cup to provide a second contact in the vicinity of thefirst electrode, the first electrode and its mounting being disposed ina plane located behind the peripheral rim of the cup when the cup is inthe relaxed condition so that initial contact with the patient's skin ismade at the peripheral rim of the cup and, following evacuation of thechannel in the cup, the internal electrode makes contact with thepatient's skin to obtain a signal at the skin surface responsive to avarying condition of the patient, characterised in that the source ofsuction comprises an individual suction pump adapted for connection tothe cup, and the resilience and form of the cup are such that, when incontact with a patient's skin and subjected to suction, the wall of thecup deforms allowing the internal electrode to be drawn down onto thepatient's skin to make the required contact therewith.

An advantage of this arrangement over the suction member of FR-A-2569976is that, for a particular size of suction cup, the suction in thechamber formed between the channel and the patient's skin surface actsover a larger area than in prior devices, so the force retaining thesuction cup against the surface is correspondingly greater. To thisincreased retaining force is further added the further retaining forcewhich originates from drawing forwardly the central electrode mountingportion within the suction cup, and this further retaining force istransmitted to the rim of the partial stiffness of the cup material.Furthermore, this increased force is concentrated on a single rim ratherthan being distributed over a multiplicity of upwardly directedsupporting rings as in the suction member of FR-A-2569976. These twofeatures--the increased retaining force and the concentrating of itsaction--create a greatly improved seal around the suction cup, and inturn permit the use of relatively simple, low pressure source means,such as a manually operated bellows, with the advantages of lightness,compactness and low cost, and also with lower suction level than thatwhich would be harmful.

Furthermore, the location of the external electrode is such that whenthe suction cup is used at an internal location such as within theuterus or womb, the two electrodes pick up signals from closely spacedpoints; this is the case of fetal scalp monitoring because it focuses onthe fetal signal rather than possibly the mother's signal.

The invention also provides a suction cup formed of resilient materialto be secured by suction to a patient's skin, comprising a peripheralwall, a centre portion enclosed by the peripheral wall to define achannel therebetween, and means for connecting the channel of the cup toa source of suction, the lower face of the centre portion being disposedin a plane behind the edge of the peripheral wall, wherein theperipheral wall and the centre portion each have a respective lipprojecting inwardly of the channel to provide the channel with anundercut configuration in cross-section into which the skin is drawn bythe suction created within the channel, the oppositely directed lipsacting to entrap the drawn in skin surface thereby enhancing thesecurity of attachment of the suction cup.

BRIEF DESCRIPTION OF THE DRAWINGS

There now follows a description of some specific embodiments of theinvention, by way of example, with reference being made to theaccompanying drawings, in which:

FIG. 1 is a plan view of a first embodiment of a resilient suction cupas part of a non-invasive medical probe according to the invention;

FIG. 2 is a vertically sectioned view taken along line 2--2 of FIG. 1;

FIG. 3 is a vertically sectioned view of a second embodiment of aresilient suction cup including a pair of electrodes;

FIG. 4 is a side elevational view of a bellows suitable for use as pumpmeans for the suction cups of FIGS. 1 to 3;

FIG. 5 is an end elevational view of the bellows of FIG. 4;

FIG. 6 is a perspective view of the suction cup of FIG. 3 and a bellowssimilar to the bellows of FIG. 4 connected together;

FIGS. 7 to 11 show further forms of bellows and other suitable pumps;and

FIG. 12 is a schematic elevational view, partly in section, which issimilar to FIG. 6, but is directed to the suction cup of FIG. 2 andincludes a monitoring device of any suitable form connected todiagnostic apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2 of the drawings, there is shown a suction cup10 which is generally circular in plan and formed of resilient material.

Suction cup 10 has a peripheral wall 11 which is substantiallycontinuous on the upper face of the suction member as shown, the suctioncup 10 having an opening 12 in its lower face.

Peripheral wall 11 defines within opening 12 a centre portion 14 whichis generally circular, and the outer periphery of which is integral withthe inner wall 16 of a single annular channel 17 formed about centreportion 14. In this embodiment, channel 17 is an annular channel, andportion 14 and channel 17 are generally concentric with the circularplan of the suction cup 10.

Channel 17 defines a recess relative to portion 14 and its shape incross-section, as seen in FIG. 2, is arched towards its upper inneraspect such that it will withstand substantial negative pressure withoutcollapsing during its intended use. This allows the suction cup to beformed from material which is pliable enough to form a good seal over anirregular surface. Outer wall 18 of channel 17, opposite inner wall 16,is formed by part of the peripheral wall 11 and terminates in an annularrim 19 which forms the outermost periphery of the suction cup 10.

The inner aspect of the annular rim 19 and the outer aspect of thecentre portion 14 at its outwardly directed face are shaped to providelips 50, 51 respectively projecting inwardly of the channel 17 to givethe channel 17 an undercut configuration in vertical cross-section whichallows the channel, during use of the suction cup 10, to entrap thedrawn in skin surface thereby enhancing the security of attachment ofthe suction cup to the fetal head.

The upper surface of centre portion 14 as shown includes an upstandingsleeve 21 which is formed integrally with centre portion 14. Sleeve 21has a central bore 21a which extends through the centre portion 14 forreception of an electrode support attached to an electrode contact platebeneath the lower surface of the centre portion as described below inconnection with the embodiment of FIG. 3.

A passageway 22 communicates the interior of channel 17 with theexterior of the suction cup 10. Passageway 22 opens into sleeve 23 whichis upstanding on the uppermost, annular ridge of channel 17 on theexterior of suction cup 10. Sleeve 23 surrounds the end of passageway22.

Referring to FIG. 3, there is shown a second embodiment of a resilientsuction member 110.

In the embodiment of FIG. 3 the shape and function of the centre portion114, inner wall 116, outer wall 118, channel 113 formed between walls116 and 118, rim 119, lips 150, 151, passageway 122 and sleeve 123 aresubstantially the same as those of their counterpart centre portion 14,walls 16, 18, channel 17, rim 19, lips 50, 51, passageway 22 and sleeve23 in the embodiment of FIGS. 1 and 2.

Centre portion 114 is of reduced diameter in the embodiment of FIG. 3 ascompared with centre portion 14 of FIGS. 1 and 2 although channel 113 isof the same width as channel 17, so the diameter of suction cup 110 isless than that of suction cup 10 of FIG. 1.

The generally arched shape of the channel 113, in verticalcross-section, likewise corresponds to the channel 17 of FIGS. 1 and 2whereby the channel will not collapse with the required negativepressure applied during use. The inwardly lipped undercut configurationof the channel 113 will also entrap the drawn in skin surface to achievethe required security of attachment of the suction cup to the fetalhead.

Passageway 122 is formed in approximately the same region of channel 113as is passageway 22 in channel 17 in the embodiment of FIGS. 1 and 2.

In the region backing centre portion 114 the wall 111 of suction cup 110is thickened into a boss having a cylindrical bore 30 which isconcentric with the suction cup 110. Bore 30 opens into sleeve 121 whichis upstanding centrally in the upper surface of suction member 110.

In the embodiment of FIG. 3, sleeve 121 and bore 30 have receivedtherein an elongate, axially extending, electrically conductiveelectrode support 31 which terminates at its lower end in a shallow conewhich protrudes through an aperture 32 formed in centre portion 114 andhas an electrode contact plate 33 secured on the conical end. The centreportion 114, thereby provides a mounting for the electrode support 31and electrode contact plate 33 which is disposed internally of thesuction cup 110. Electrode contact plate 33 is of a kind suitable forthe measuring and/or monitoring to be undertaken through application ofthe suction cup 110. The electrode contact plate 33 may optionally beformed of or coated with a substance improving the conduction of signalsfrom the patient to the electrode. The plate may be formed from metaland may have a roughened or knurled surface to enhance contact with theskin particularly in the case of a hair covered scalp as indicated at33a.

At its upper end, electrode support 31 includes a bore 34 which receivesa live electrode wire 36 which is in electrical contact with theelectrode support and hence the electrode contact plate 33.

Electrode wire 36 is housed within a silicone rubber sheath 37 which isfitted over the end of sleeve 121 by virtue of the resilience of itsmaterial.

Twisted about live electrode wire 36 within sheath 37 is a neutralelectrode wire 38. The conductor 39 of neutral wire 38 is bared over apart of its length to permit the conductor 39 to pass between sheath 37and sleeve 121. Conductor 39 then passes up the outside of sheath 37 toa region in which the insulation of neutral wire 38 is re-formed onconductor 39 and in which neutral wire 38 is coiled about the exteriorof sheath 37.

Neutral wire 38 is coiled several times about sheath 37 in theembodiment of FIG. 3 and at its upper end the conductor 39 iselectrically connected to a sliding electrical contact or secondelectrode 41 comprising a metallic sleeve external of the suction cup10.

A resilient, insulating outer sleeve 42 is fitted about the exterior ofsheath 37 to protect the exposed conductor 39 and the lowermost coils ofcoiled wire 38 against accidental damage.

In FIGS. 4 to 5 there is shown a simple, manually operated bellows 24for use with the suction cup 10 or 110 to complete the non-invasiveprobe. The bellows 24 may be of generally oval cross-section as shown inFIG. 5 or may be circular in cross-section as shown in FIG. 6, andincludes a resiliently compressible, variable volume pumping chamber 26which is closed at one end by an integral end wall 26a and has anintegral nozzle 27 communicating with the exterior of the chamber at theopposite end. The resilient walls of the pumping chamber 26 tend to biasthe bellows 24 towards its expanded condition. Preferably the bellows 24is connected by a flexible tube or conduit connection 28 to the suctioncup 110 as illustrated in FIG. 6 to enable the bellows to be locatedremotely from the cup. This arrangement is particularly necessary in thecase where the suction cup is applied to the head of an unborn fetusstill within the mother's uterus so that the bellows can be located andoperated externally of the mother.

Compressing of the pumping chamber 26 of the bellows 24 in an axialdirection causes expulsion of air from chamber 26 via nozzle 27.Releasing of the pumping chamber causes the pumping chamber 26 to tendto resume its uncompressed configuration, with the resultingsimultaneous increase in its volume causing the bellows to be operableas a simple suction pump. More complex suction pumps, for exampleincluding selectively operable non-return valve means, may be used withthe suction members of the invention instead of the bellows of FIGS. 4and 5, but the bellows 24 has been found to be sufficiently powerful tooperate the suction member 10 and is, in addition, light, reliable,easily sterilised and cheap to manufacture.

The operation of the resilient suction cup of the invention will now bedescribed in relation to the embodiment of FIGS. 1 and 2, although itshould be realised that the operation of the embodiment of FIG. 3 takesplace in a similar manner.

Prior to application of the suction cup 10 to the skin of a patient, anelectrode assembly such as 31, 33, 36, 38 of FIG. 3 is inserted into thebore of the sleeve 21 in the centre portion 14, the electrode contactplate 33 being beneath the lower surface of the centre portion 14. Thedimensions of the bore of sleeve 21 are so chosen that the electrodesupport 31 is frictionally retained within the bore, with saidpliability of the material of the suction cup allowing the electrodecontact plate 33 o to assume appropriate orientation to permit it toreceive electrical signals from the patient.

The electrode is suitable for monitoring characteristics of a patientsuch as a fetus or a neonate, and it may be connected via suitablewiring to diagnostic monitoring apparatus.

The nozzle 27 of the bellows 24 is connected in this embodiment by pipe28 to the sleeve 23 surrounding the end of passageway 22. The pipe 28 isa sealing fit in sleeve 23, so that the bellows may be operated towithdraw air from channel 17 via passageway 22.

With the suction cup 10 thus arranged, the pumping chamber 26 is axiallycompressed to expel air therefrom, via passageway 22 and opening 12. Inthat condition the suction cup 10 is applied to, for example, the scalpof a fetus with the rim 19 of the suction member 10 in sealing contactwith the surface of the scalp. The air line 28 and cable 36, 38 extendout through the vagina, and the second electrode 41 on the cable bearsagainst and is in electrical contact with the mother at a location notfar away from the first internal electrode, i.e. the position of theelectrode contact plate 33. The cable is connected to anelectrocardiogram machine or other diagnostic apparatus, and the bellowsis accessible outside the mother.

Within the suction cup 10, a chamber then exists between the inner sideof peripheral wall 11 and the surface of the scalp, the chamber beingsealed about rim 19 of wall 11. Releasing of the pumping chamber 26causes it resiliently to tend to return to its uncompressedconfiguration, withdrawing air from the chamber in the suction cup andadhering the member 10 by suction to the surface of the scalp.

As a result of the shape of suction cup 10, the partial vacuum in thechamber resulting from operation of the bellows as aforesaid actsinitially over the entire area of the surface of the scalp enclosedwithin rim 19.

However, the suction cup 10 tends to deform as the partial vacuum isapplied, with the result that central portion 14 is drawn downwardly,against the resilience of the suction cup material, whereby theelectrode contact plate 33 engages the surface of the scalp. Theelectrode contact plate 33 is thereby ideally positioned for monitoringpurposes in contact with the scalp, the circuit being completed throughthe second electrode 41 which is in contact with the mother at a pointclose to the suction cup 10 and which, of course, is in contact with thefetal head. In practice, it is found that the close proximity betweenthe second electrode 41 and the area of application of the internalelectrode within the suction cup 10 is important to ensure that thedesired signal transmitted by the probe to the electrocardiogram machineor other diagnostic apparatus is representative of the fetus beingmeasured or monitored and not of the mother.

As the electrode plate 33 contacts the scalp surface, the shape of thesingle chamber formed between the suction cup and the scalp surfacebecomes substantially annular, conforming to the channel 17, and theforce pulling the plate 33 towards the scalp surface (calculated as thearea of the plate multiplied by the lowering of the pressure, asprevailing in the channel, below atmospheric) is transmitted via walls16 and 18 to rim 19. The excess of the atmospheric pressure over thepressure prevailing inside the channel acts on the large, annular areaof the scalp surface enclosed between the rim 19 and the electrodecontact plate 33 and approximately half of the resulting force actsvertically downwards through the rim 19 to retain the suction cup 10strongly secured to the scalp surface and to prevent air or ambientliquids seeping into the suction cup. Since the retaining force acts ona single rim 19 the overall security of holding the suction cup inposition on the fetal head and hence the sealing of the cup against theskin surface is greater than in arrangements where the retaining forceacts via a plurality of rims or walls.

During the application of suction, the annular channel 17 entraps thedrawn in skin surface of the scalp which conforms to the archedcross-sectional shape of the channel, the undercut configurationdescribed above enhancing the security of the suction cup 10 to thefetal head. The moderate sub-atmospheric pressure applied by the bellows24 is maintained to act against perturbations tending to dislodge thecup.

After the monitoring process is completed, release of the suction cup 10is readily achieved by axially re-compressing the pumping chamber 26 toblow air via nozzle 27 through passageway 22 to increase the pressure inthe channel 17 and to permit withdrawal of the suction cup from thescalp surface rather than just ripping the cup off.

Reference is now made to FIGS. 7 to 11 of the drawings which show anumber of modifications to the arrangements described above. Firstly, inFIG. 7, a modification to the bellows 26 is illustrated in which theclosed end wall 26a of the bellows is formed with a flap valve 26b whichcan open to release air from the bellows through a port in the end wall26a as the bellows is compressed. Thus, if it is necessary tore-establish the suction holding the suction cup to the head of thefetus whilst the probe is in use, the bellows 26, which as describedabove is outside the mother, can be recompressed allowing air from thebellows to escape through the flap valve 26b and not be transmitted tothe suction cup, and the user's thumb acting on the end wall of thebellows can then be moved over the flap valve to close the valve port asthe bellows is allowed to expand to re-draw the vacuum in the suctioncup.

FIG. 8 shows a different form of non-return valve on the end wall 26c ofthe bellows in which a short tube 40 projects from the end wall of thebellows and has a ball or slug 241 held captive in the tube to allowrelease of air through the tube when the bellows is compressed. In thisembodiment, in the outer end of the tube is a grid to retain the slug241 therein without closing off the end. When the bellows is allowed toexpand, the slug 241 is drawn against the valve seat to block theopening between the tube 40 and bellows 26 so that the bellows thendraws vacuum in the suction cup. For releasing the suction cup withoutdamaging the skin of the fetus, the valve is held closed when thebellows is compressed.

The resilient walled bellows 26 described above provides a convenientform of hand operated pump for drawing vacuum in the suction cup, but itwill be appreciated that other forms of pump means can be utilised andFIGS. 9 and 10 show syringes 242, 43 respectively adapted to act aspumps for evacuating the suction cup. In FIG. 9 the pump has an internaltension spring 44 so that when the plunger 45 of the pump has beendepressed and the suction cup is applied to the patient's skin, theplunger can be released and, under the action of the spring, the plungerdraws vacuum in the suction cup as it is moved along the cylinder 46 ofthe syringe. FIG. 10 shows a similar arrangement in which the spring 47is a compression spring located externally between the head 48 of theplunger 45 and the end of the cylinder 46 of the syringe which isopposite to the nozzle end. FIG. 11 shows a modified form of syringe inwhich the piston 250 of the plunger 251 has a non-return valve 252 sothat as the plunger is depressed, air is released to the back of thepiston and is not directed towards the suction cup. When the plunger 251is released and allowed to return, for example, by a spring 44 or 47,the non-return valve 252 closes automatically so that the returnmovement of the plunger draws vacuum in the suction cup as describedabove.

The above embodiments relate to a probe for non-invasively monitoring,generally the heart beat of a fetus, by the use of suction to secure thesuction cup 10 or 110 to the fetal head, and the pair of electrodes 33,41 connected to diagnostic apparatus.

Additionally or alternatively, it may be desired to monitor otherconditions of the patient.

With reference to FIG. 12, there is illustrated an embodiment in whichthe suction cup 10 of FIGS. 1 and 2 has a monitoring and/or measuringdevice 60 connected by wires 61, 62 to the schematically illustrateddiagnostic apparatus 63, the device 60 passing through bore 21a in thesleeve 21 upstanding from the central portion 14 of the cup and makingskin contact with the patient. Bellows 24 is also connected by pipe 28to sleeve 23. Application of the suction cup is the same as describedpreviously.

However, it will be appreciated that the monitoring and/or measuringdevice may be provided as an additional device or instead of theelectrode monitoring device of the preceding embodiments.

More particularly, at least one additional device may be employed forobtaining other biological information signals, from which signalsinformation is deduced concerning fetal condition, by application of thedevice to the skin surface.

One example is the use of fibre optics for the emission and reception oflight at the skin surface, such as for monitoring skin blood perfusion.The fibre optics connected to the diagnostic apparatus would passthrough the sheath 37, which would be enlarged if necessary, and thesleeve 21 or 121 in the centre portion of the respective suction cup,and also through apertures in the electrode contact plate 33, ifretained, into contact with the skin surface.

A transducer may be employed for the conversion of biologicalinformation into an electric signal, the information being, for example,the amounts of oxygen and/or carbon dioxide in the blood. Again thetransducer would be connected back by wires through the centre portionof the suction cup to the diagnostic apparatus.

A thermistor or other similar device may measure skin surfacetemperature. The thermistor mounted on the bottom face of centre portion14 or 14, would contact the fetal skin, through an aperture in theelectrode contact plate 33 if retained, and have a pair of wires passingback through the centre portion 14 or 114, and if desired the sheath 37,to the diagnostic apparatus.

Another example is the use of piezo crystals for the generation andreceiving of ultrasound signals. The crystals would be mounted on thebottom face of centre portion 14 or 114, with apertures in the electrodecontact plate 33 if retained, wires from the crystals again passing backthrough the centre portion of the suction cup to the diagnosticapparatus.

A further example is the use of at least two oximetry devices mounted inthe same manner as the above-mentioned piezo crystals and connected bywires to the diagnostic apparatus. The oximetry devices would measurehaemoglobin oxygen saturation.

It will again be appreciated that all these additional devices wouldpass through the central portion 14 or 114 of the suction cup to makecontact with the skin surface. With regard to the construction of thesuction cup shown in FIG. 3, the devices would contact the skin throughthe electrode contact plate 33. However, in the case of an enlargedcentre portion being provided, for example as shown in FIG. 2, this maynot be necessary.

The above examples are, of course, not exhaustive, and other similaruses are envisaged within the scope of the invention.

What we claimed is:
 1. A non-invasive medical probe for monitoring apatient's condition comprising:a suction cup having a resilient wallwith peripheral rim for application to a patient's skin; a source ofsuction which comprises an individual suction pump connected to saidcup; a first and a second non-invasive skin contact electrode adaptedfor connection to a diagnostic apparatus, the first electrode beingdisposed internally within the cup on a mounting located centrallywithin the cup to leave a channel encircling the first electrode withinthe peripheral rim to be evacuated for securing the cup to the skin, andthe second electrode being disposed on an external surface of the probeadjacent to the cup whereby the second electrode provides a secondcontact in the vicinity of a contact of the first electrode, the firstelectrode and said mounting being disposed in a plane located behind theperipheral rim of the cup when the cup is in a relaxed or non-suctioncondition so that initial contact with the patient's skin is made at theperipheral rim of the cup and, following evacuation of the channel inthe cup by said suction pump, the first electrode makes contact with thepatient's skin to obtain a signal at the skin surface responsive to avarying condition of the patient, and the cup having a resilience andform such that, when the cup is in contact with a patient's skin andsubjected to suction, the wall of the cup deforms allowing the firstelectrode to be drawn down onto the patient's skin to make contacttherewith.
 2. A non-invasive medical probe as claimed in claim 1,wherein the mounting for locating the first electrode comprises a centreportion which is integral with the peripheral rim of the cup and whichis disposed within the cup to define an inner wall of the channelsurrounding the first electrode mounted on the centre portion.
 3. Anon-invasive medical probe as claimed in claim 1, wherein a cable isconnected to the suction cup comprising electric wires for connection tothe respective electrodes, and said first electrode being connected toone of said wires and said second electrode comprising a metallic sleeveencircling the cable adjacent to the suction cup and to which a secondone of said wires is electrically connected.
 4. A non-invasive medicalprobe as claimed in claim 1 wherein the pump for drawing vacuum withinthe channel in the cup includes a variable volume chamber connected tothe channel in the cup and resilient means for urging the chamber intoan expanded condition to maintain a partial vacuum drawn by the pump inthe channel in the cup.
 5. A non-invasive medical probe as claimed inclaim 4, wherein said pump includes an air pressure release valve whichis in communication with said chamber for discharging air from thechamber without applying pressure to the air within the channel of thecup.
 6. A non-invasive medical probe as claimed in claim 5, wherein therelease valve for the chamber comprises a releasable one-way valve.
 7. Anon-invasive medical probe as claimed in claim 1, wherein the pumpcomprises a bellows providing a chamber which is collapsible todischarge air therefrom against the action of resilient means to expandthe bellows to draw vacuum in the channel connected thereto.
 8. Anon-invasive medical probe as claimed in claim 7, wherein the bellowshas resilient walls formed to bias the bellows towards its expandedcondition.
 9. A non-invasive medical probe as claimed in claim 8 whereinthe bellows includes a resilient flap valve for release of air therefromwhen the bellows is compressed and to prevent entry of air thereto whenthe bellows is released.
 10. A non-invasive medical probe as claimed inclaim 9, wherein the bellows is a generally closed cylindrical form, oneend wall of which has a conduit connection to the channel in the suctioncup and the opposite end wall of which is formed with a port controlledby said flap valve.
 11. A non-invasive medical probe as claimed in claim1, wherein the pump comprises a cylinder and a reciprocable piston forvarying the volume of a chamber provided in the cylinder, spring meansbeing provided for biassing the piston in a direction to expand thechamber and thereby draw vacuum in the resilient suction cup connectedto the chamber.
 12. A non-invasive medical probe as claimed in claim 11,wherein the piston has a plunger projecting outwardly of the cylinderfor manual operation of the piston.
 13. A non-invasive medical probe asclaimed in claim 12, wherein the piston includes a one-way valve torelease air from the variable volume chamber of the cylinder connectedto the channel of the suction cup prior to application of the suctioncup to the patient's skin, and then to draw vacuum in the channel tohold the cup on the patient's skin by the action of the spring means onthe piston in trying to restore the chamber of the cylinder connected tothe suction cup to its expanded position.
 14. A non-invasive medicalprobe as claimed in claim 1 wherein said suction cup includes means forconnecting the channel of the cup to said source of suction, and theperipheral rim and the mounting located centrally within the cup eachhave a respective lip projecting inwardly of the channel to provide thechannel with an undercut configuration in cross-section into which theskin is drawn by the suction created within the channel, the oppositelydirected lips acting to entrap the drawn in skin surface therebyenhancing the security of attachment of the suction cup.
 15. Anon-invasive medical probe as claimed in claim 14, wherein the channelis defined by an arched portion of the wall of said suction cup whicharched portion is shaped so as to resist collapse when subjected tosuction.
 16. A non-invasive medical probe as claimed in claim 14,further comprising a monitoring and/or measuring device which is inaddition to said first electrode and is supported in said mounting formaking contact with the patient's skin to obtain a biologicalinformation signal at the skin surface responsive to one or moreconditions of the patient.
 17. A non-invasive medical probe as claimedin claim 14, wherein the means for connecting the channel to a source ofvacuum pressure is a sleeve directed outwardly from the wall of thesuction cup and said sleeve having a passageway which extends throughthe wall of the suction cup into communication with said channel.
 18. Anon-invasive medical probe as claimed in claim 14, wherein theconnecting means includes a flexible conduit which is dimensioned andarranged to allow the suction cup to be secured to a fetal scalp by wayof the source of suction located externally of the patient.
 19. Anon-invasive medical probe as claimed in claim 1, further including amonitoring and/or measuring device which is in addition to said firstand second electrodes and is supported in the mounting of the cup, andsaid monitoring and/or measuring device being adapted for connectionwith a diagnostic apparatus.
 20. A non-invasive medical probe as claimedin claim 1, wherein said first electrode includes an electrode contactplate with a roughened surface.
 21. A non-invasive medical probe formonitoring a patient's condition, comprising:a resilient walled suctioncup having a peripheral rim for application to a patient's skin; asuction pump connected to said cup; a first and a second non-invasiveskin contact electrode adapted for connection to a diagnostic apparatus,the first electrode having an electrode supply being slidingly receivedwithin a bore formed in said suction cup and an electrode contact platedisposed internally within the cup on a mounting located centrallywithin the cup to leave a channel encircling the first electrode withinthe peripheral rim to be evacuated for securing the cup to the skin, andthe second electrode being disposed on an external surface of the probeadjacent to the cup whereby the second electrode provides a secondcontact in the vicinity of a contact of the first electrode, theelectrode contact plate of said first electrode and said mounting beingdisposed in a plane located behind the peripheral rim of the cup whenthe cup is in a relaxed or non-suction condition so that initial contactwith the patient's skin is made at the peripheral rim of the cup and,following evacuation of the channel in the cup by said suction pump, theelectrode plate of said first electrode makes contact with the patient'sskin to obtain a signal at the skin surface responsive to a varyingcondition of the patient; and said cup having a resilience and form suchthat, when in contact with a patient's skin and subjected to suction,the wall of the cup deforms allowing the first electrode to be drawndown onto the patient's skin to make the required contact therewith, theperipheral rim and the centrally located mounting each have a respectivelip projecting inwardly of the channel to provide the channel with anundercut configuration in cross-section into which the skin is drawn bythe suction created within the channel, the oppositely directed lipsacting to entrap the drawn in skin surface thereby enhancing thesecurity of attachment of the suction cup.